Lance L. Lobban

School of Chemical Engineering. University of Oklahoma

100 E. Boyd St, Norman OK 73019

(405) 325-5814, fax (405) 325-5813, e-mail lobban@mailhost.ecn.ou.edu

Admicellar catalysis and photocatalysis are two ‘nonclassical’ examples of catalytic processes. Admicellar catalysis uses surfactant monolayers or bilayers physically adsorbed on high surface areas supports to catalyze liquid phase reactions. The advantages of admicellar catalysis include elimination of organic solvents, easy separation of products from the catalyst, and higher reaction rates than observed in micellar catalysis. We have demonstrated admicellar catalysis for a model reaction, the hydrolysis of trimethyl orthobenzoate to methyl benzoate. The admicelles’ catalytic activity is comparable to that of micelles of the same surfactant. The rate of hydrolysis also depends strongly on the pH and on the extent of surfactant adsorption, possibly because of a shift in surfactant aggregate morphology as the amount adsorbed increases. Current studies are examining the influence of pore size on the amount and morphology of adsorbed surfactant aggregates. We have synthesized MCM materials with narrow pore size distributions and studied the adsorption isotherms using surfactants with varying hydrocarbon tail lengths.

We are also trying to develop photocatalysts that are both very active and are easy to use in indoor air applications. Our approach is to develop TiO₂ or TiO₂/SiO₂ aerogels whose properties allow the use of relatively large particles in fixed beds. Although the TiO₂ aerogels have low crystallinity, they show reasonable photocatalytic activity, comparable to pure anatase powders. The crystallinity can be increased with heat treatment, but the porosity and surface area both decrease. We are investigating other means to improve the photocatalytic activity of the aerogels.

1. We are interested in developing and testing new photocatalytic materials. Our studies have all been based on titania materials, but others are of interest. An area of particular interest in the aerogel photocatalysts or other nano-structured materials. We have capabilities for UV, XRD, and (soon) XPS characterization of the synthesized materials, as well as TEM and SEM and physical characterization.
2. We are currently involved in studies of adsorption of surfactants on high surface area materials. The pore size distribution and the surfactant size play important roles in the morphology of the surfactant aggregate that forms. We would like to understand this phenomena better. Reactions that are currently carried out in organic solvents, micelle-catalyzed reactions, and phase transfer catalyzed reactions are all applications for admicellar catalysis.